Xearth sets the X root window to an image of the Earth, as
seen from your favorite vantage point in space,  correctly
shaded  for  the  current position of the Sun. By default,
xearth updates the displayed image every five minutes. The
time between updates can be changed with the -wait option.
Xearth  can  also  render  directly into PPM and GIF files
or  into  its  own window  instead  of drawing in the root
window.
